Directions: Preheat oven to 350°F (180°C).
Place potatoes in a large bowl and drizzle with 2 tbsp (30 mL) oil; season liberally with salt and pepper. Place directly on centre rack and bake for 70 to 75 minutes or until tender.
Meanwhile, heat remaining 1 tbsp (15 mL) oil in a medium saucepan over medium heat; cook onion until golden, 6 to 7 minutes. Add garlic; cook an additional minute. Crumble beef into pan and brown, breaking apart with a fork as you go. Sprinkle chili powder and cumin over, stir in tomato paste and broth. Add beans, bring to a gentle boil and cook for 6 to 8 minutes or until thickened; season with salt, pepper and hot sauce to taste. Set aside and keep warm.
In a separate pot over medium heat, melt 2 tbsp (30 mL) butter; whisk in flour. Slowly pour milk over butter mixture, whisking as you go, until no lumps remain. Bring to a boil and cook until thickened, about 1 minute. Whisking constantly, add cheese in 3 handfuls, stirring between each until cheese is melted before adding more. Season sauce with salt and pepper to taste; stir in cayenne.
Split top of potatoes and fluff flesh with a fork. Divide remaining 4 tbsp (60 mL) butter between them. Divide roughly half of the cheese sauce between the potatoes, then the chili; top with remaining cheese sauce. Sprinkle each with an equal amount of green onion.